When you say "whole beat," do you mean a "whole note" which would essentially be 4 beats (assuming 4/4 time signature)? This would mean the quantize would start only on the "1" beat if I'm understanding you correctly.
As far as I know you can't set this in XDJ. That said, the quantize function snaps quite well to the grid, so you should be able to snap to the beat you want unless you're playing at a Happy Hardcore tempo. ;-)